Distributed processing method, system, and computer product

ABSTRACT

A distributed processing method of a system in which communications apparatuses communicate data by multi-hop communication is executed by a given communications apparatus among the communications apparatuses. According to the method, the given communications apparatus executes a given process based on a result of a first process executed by a first communications apparatus that among the communications apparatuses, communicates directly with the given communications apparatus and operates using power stored in a charging device charged by power generated from energy obtained corresponding to an environment where installed. The given communications apparatus executes the given process when receiving the result of the first process from the first communications apparatus. The given communications apparatus further determines whether a given period has elapsed since receiving the result of the first process, and transmits a result of the given process to the first communications apparatus when determining that the given period has elapsed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication PCT/JP2013/069567, filed on Jul. 18, 2013 and designatingthe U.S., the entire contents of which are incorporated herein byreference.

FIELD

The embodiments discussed herein are related to a distributed processingmethod, a system, and a computer product.

BACKGROUND

A conventional technique called energy harvesting involves generatingelectrical power using energy obtained corresponding to the localinstallation environment. Another conventional technique distributesprocessing among plural communications apparatuses. One relatedtechnique, for example, detects output from communications apparatusesthat execute distributed processing of analysis processes, determinesthat a failure has occurred at a communications apparatus from whichthere is no output, and resumes the analysis processing by recoveringthe failed communications apparatus via a communications apparatus thatmanages the plural communications apparatuses (for example, refer toJapanese Laid-Open Patent Publication No. 2010-231295).

Nonetheless, with the conventional techniques above, when distributedprocessing is to be performed by communications apparatuses that operateusing power generated from energy obtained corresponding theenvironment, the operation of a communications apparatus that executedthe processing may be suspended consequent to the power being exhausted.In such instances, successive distribution of plural processes to thecommunications apparatuses is difficult.

SUMMARY

According to an aspect of an embodiment, a distributed processing methodof a system in which plural communications apparatuses transmit andreceive data by multi-hop communication, is executed by a givencommunications apparatus among the plural communications apparatuses.The distributed processing method including executing, by a givencommunications apparatus being among the plurality of communicationsapparatuses, a given process based on a result of a first processexecuted by a first communications apparatus that is among the pluralityof communications apparatuses, communicates directly with the givencommunications apparatus, and operates using power stored in a chargingdevice charged by power generated from energy obtained corresponding toan environment where the first communications apparatus is installed,the given communications apparatus executing the given process whenreceiving the result of the first process from the first communicationsapparatus; determining, by the given communications apparatus, whether agiven period has elapsed since receiving the result of the firstprocess; and transmitting, by the given communications apparatus, aresult of the given process to the first communications apparatus whendetermining that the given period has elapsed.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are diagrams depicting an operation example of adistributed processing method of a system according to a firstembodiment;

FIG. 2 is a block diagram depicting an example of hardware configurationof a node;

FIG. 3 is a block diagram depicting an example of hardware configurationof an inspector terminal;

FIG. 4 is a block diagram depicting a functional example of the systemaccording to the first embodiment;

FIG. 5 is a diagram depicting a sequence of distributed processing ofthe nodes according to the first embodiment;

FIG. 6 is a diagram depicting one example of a job structure accordingto the first embodiment;

FIG. 7 is a flowchart depicting an example of a procedure of a jobassignment process according to the first embodiment;

FIG. 8 is a flowchart depicting an example of a procedure of a jobexecution process according to the first embodiment;

FIG. 9 is a flowchart depicting an example of a procedure of a jobaggregation and reassignment process according to the first embodiment;

FIG. 10 is a flowchart depicting an example of a procedure of a jobaggregation process;

FIG. 11 is a diagram depicting an operation example of the distributedprocessing method according to a second embodiment;

FIG. 12 is a block diagram depicting a functional example of the systemaccording to the second embodiment

FIG. 13 is a diagram depicting a sequence of distributed processing bythe nodes according to the second embodiment;

FIG. 14 is a diagram depicting an example of the job structure accordingto the second embodiment;

FIG. 15 is a flowchart depicting an example of a procedure of the jobassignment process according to the second embodiment;

FIG. 16 is a flowchart depicting an example of a procedure of the jobexecution process according to the second embodiment; and

FIG. 17 is a flowchart depicting an example of a procedure of the jobaggregation and reassignment process according to the second embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments of a disclosed distributed processing method, system, anddistributed processing program will be described in detail withreference to the accompanying drawings.

FIGS. 1A and 1B are diagrams depicting an operation example of thedistributed processing method of the system according to a firstembodiment. A system 100 includes an inspector terminal 101 and pluralcommunications apparatuses. The communications apparatuses are referredto as “nodes” hereinafter. The nodes included in the system 100 includea master node, which is a specified node, and slave nodes, which arenodes other than the specified node. Hereinafter, a master node issimply called a “master”. Further, a slave node is simply called a“slave”. As depicted in FIG. 1A, the masters include masters #0, #1 andthe slaves include slaves #a_0 to #a_N, #b_0 to #b_N, #c_0 to #c_N, #d_0to #d_N, and #e_0 to #e_N.

Hereinafter, slaves #a_0 to #a_N, #b_0 to #b_N, #c_0 to #c_N, #d_0 to#d_N, and slaves #e_0 to #e_N will be referred to as “the slaves”.Further, masters #0, #1 and the slaves will be referred to as “thenodes”.

Each of the nodes is a communications apparatus that has an energyharvesting device that generates electrical power using energy obtainedcorresponding to the environment in which the node is installed andoperates using electrical power stored by a charging unit charged withthe electrical power generated by the energy harvesting device. Thenodes are disposed in a given area R. The given area R, for example, isan area filled with a substance such as concrete, soil, air, etc. Thenodes activate when sufficiently charged and perform intermittentoperation of transmitting data and sleeping. Further, the electricalpower generated by the energy harvesting device is limited andtherefore, the nodes use short distance radio, which consumes minimalpower, and communicate data by multi-hop communication.

The nodes communicate data by multi-hop communication along a specifiedcommunication path. The specified communication path has master #0 as astart point and master #1 as an end point. Further, when pluralspecified communication paths are present in the system 100, thespecified communication paths share master #0 and master #1, but do nothave slaves in common. The specified communication path, for example,may be determined by an algorithm that determines communication paths orby an instruction from the inspector terminal 101, etc.

As an example of an algorithm that determines communication paths, forinstance, master #0 appends node identification information of master #0to a signal and transmits the signal to a node with which directcommunication is possible. A given slave that receives the signalappended with the identification information of master #0 appends thenode identification information of the given slave to the receivedsignal and transmits the signal to a node with which directcommunication is possible, if the given slave has not transmitted asignal and the node identification information of the given slave is notin the received signal. The contents of the signal received by master #1are information representing the communication path. Master #1 gives tothe slaves by multi-hop communication, notification of identificationinformation of adjacent nodes of each slave among the slaves on thecommunication path. The slaves store to a storage apparatus, theidentification information of the adjacent nodes of each slave among theslaves on the communication path.

In the example depicted in FIG. 1A, the given area R has 5 communicationpaths. The first communication path is a communication path configuredby master #0, slaves #a_0 to #a_N, and master #1. The secondcommunication path is a communication path configured by master #0,slaves #b_0 to #b_N, and master #1. The third communication path is acommunication path configured by master #0, slaves #c_0 to #c_N, andmaster #1. The fourth communication path is a communication pathconfigured by master #0, slaves #d_0 to #d_N, and master #1. The fifthcommunication path is a communication path configured by master #0,slaves #e_0 to #e_N, and master #1.

The nodes may have sensors. The nodes use the respective sensors anddetect the temperature, humidity, stress, etc. in the given area R. Theinspector terminal 101 aggregates to a server, data related to thedetection by the nodes and uses the data for analysis processing. Here,since the data is collected for each of the nodes, the data volumebecomes great, placing a load on the inspector terminal 101. Therefore,the system 100 according to the first embodiment uses the computingcapacity of the nodes to distribute and perform the analysis processingand thereby, facilitates a reduction of the load occurring when theinspector terminal 101 collects the data.

Nonetheless, when the analysis processing is distributed and performedby the nodes, since the nodes operate intermittently, even if the masterattempts to cause a slave to execute the processing, the slave operatesintermittently and consequently, assignment of processing to the slaveduring suspension of the slave is difficult. Here, if configuration issuch that the master transmits a signal inquiring whether the slave isoperating, repeated signal transmission occurs increasing the powerconsumption of the master. Further, if the remaining power level ofplural nodes is sufficient, although distributed processing can beperformed one session at a time by the nodes, the operation of each nodethat has transmitted the processing results for 1 session is suspendedand when distribution to more than the number of the nodes is desirable,assignment of the processing is difficult.

Thus, in the system 100 according to the present embodiment, after themaster receives a processing result from a given slave, the mastertransmits to the given slave after a given period elapses, a processingresult obtained by the master. As a result, the system 100 can passprocessing results during operation of the slaves, whereby slaves can becaused to execute new processing that uses processing results.

More specifically, master #0 assigns processing to the slaves. Theslaves execute the processing and master #1 aggregates the processingresults. Master #1 further assigns to the slaves, processing that usesthe aggregated results. The slaves execute the processing and master #0aggregates the processing results.

FIG. 1B depicts a communication sequence of slave #a_N that communicatesdirectly with master #1 and master #1, after master #0 has assignedprocessing to the slaves. Further, rectangle 111 of slave #a_Nrepresents the remaining power level of the charging unit of slave #a_Naccording to time points. For example, at time t0, slave #a_N isindicated to be sufficiently charged.

From time t0 to t1, slave #a_N executes a first process and transmitsfirst process results to master #1. Here, the first process isprocessing assigned by master #0. A program describing the contents ofthe first process may be stored to a storage area of the node by themanager of the system 100 via the inspector terminal 101, after the nodeis disposed or after the specified communication path is determined, ormay be a program that is transmitted by master #0 and enables executionof the processing contents. The contents of the first process is notlimited and, for example, may include an addition process of adding datareceived by slave #a_N and data obtained from the sensor of slave #a_N,and a process of incrementing a hop count of the data received by slave#a_N.

At time t1, slave #a_N transmits a result of the first process to master#1 and since no power remains, suspends operation. The result of thefirst process, for example, is the result of the addition and theincremented hop count.

During some instance between time t1 and time t2, master #1 executes agiven process based on the result of the first process. The givenprocess is processing related to the first process. A program describingthe contents of the given process, for example, may be stored to astorage area of the node by a manager of the system 100 via theinspector terminal 101, after the node is disposed or after thespecified communication path is determined. The given process, forexample, is a process of calculating an average from the data and hopcounts of the first process.

Master #1 determines whether the given period has elapsed sincereceiving the result of the first process. As a determination method,for example, master #1 records the clock pulse of a given processor inmaster #1 when the result of the first process is received andperiodically refers to the clock pulse count to determine whether thegiven period has elapsed.

The given period is a power charging period from the exhaustion of theremaining power of the slaves until a power level enabling operation isreached. In actuality, the length of the given period may be determinedbased on measurement results obtained at the time of node manufacturing,or may be determined based on the amount of power generated by theenergy harvesting device when the node is installed. For example, thegiven period may be as short as 1 minute and as long as 10 minutes.

At time t2, if the given period has been determined to have elapsed,master #1 transmits the result of the given process to slave #a_N. As aresult, slave #a_N uses the result of the given process to again executeprocessing. Hereinafter, the system 100 according to the firstembodiment will be described with reference to FIGS. 2 to 10.

FIG. 2 is a block diagram depicting an example of hardware configurationof the node. In the example depicted in FIG. 2, slave #a_0 is taken asan example and hardware configuration of slave #a_0 is depicted. Othernodes including master #0, #1, slaves #a_1 to slave #a_N, slaves #b_0 to#b_N, slaves #c_0 to #c_N, slaves #d_0 to #d_N, and slaves #e_0 to #e_Nhave a hardware configuration identical to that of slave #a_0. Slave#a_0 has a microprocessor (hereinafter, referred to as a micro controlunit (MCU)) 201, a sensor 202, a wireless communications circuit 203,random access memory (RAM) 204, read-only memory (ROM) 205, non-volatilememory 206, an antenna 207, a harvester 208, a battery 209, and a powermanagement unit (PMU 210). Slave #a_0 further has a bus 211 thatconnects the MCU 201, the sensor 202, the wireless communicationscircuit 20, the RAM 204, the ROM 205, and the non-volatile memory 206.

The MCU 201 is a computation processing apparatus that governs overallcontrol of slave #a_0. For example, the MCU 201 processes the dataobtained by the sensor 202. The sensor 202 is an apparatus that detectsa given change at the installation site. The sensor 202, for example,may be a piezoelectric device that detects voltage at the installationsite, a device that detects temperature, a photoelectric device thatdetects light, and the like. The antenna 207 transmits and receivesradio waves wirelessly communicated with the inspector terminal and/orother nodes. The wireless communications circuit 203 (radio frequency(RF)) outputs received wireless radio waves as a reception signal andtransmits a transmission signal as wireless radio waves, via the antenna207. The wireless communications circuit 203 suffices to be acommunications circuit employing short range radio enablingcommunication with other nodes within a vicinity of several tens ofcentimeters.

The RAM 204 is a storage apparatus storing therein transient data ofprocessing at the MCU 201. The ROM 205 is a storage apparatus storingtherein process programs executed by the MCU 201. The non-volatilememory 206 is a rewritable storage apparatus and retains given datawritten thereto, even when power supply ceases. For example, flashmemory and the like may be employed as the non-volatile memory 206.

The harvester 208 is the energy harvesting device described withreference to FIG. 1 and is an apparatus that generates power based onthe external environment at the installation site of slave #a_0, suchas, for example, energy changes in light, vibration, temperature,wireless radio waves (reception radio waves), etc. Further, theharvester 208 may generate power according to changes detected by thesensor 202. The battery 209 is an apparatus that stores the powergenerated by the harvester 208. In other words, slave #a_0 does notrequire a secondary battery or external power source and internallygenerates power for operation. The PMU 210 is an apparatus that controlsthe supply of the power stored by the battery 209, as a drive source tothe components of the node.

FIG. 3 is a block diagram depicting an example of hardware configurationof the inspector terminal. The inspector terminal 101 has a processor(central processing unit (CPU) 301, large capacity ROM 302, RAM 303,non-volatile memory 304, an interface (input/output (I/O)) circuit 305,a wireless communications circuit 311, an antenna 312, and a network I/F313. The CPU 301 may be more sophisticated than the MCU 201 of thenodes. The inspector terminal 101 further has a bus 306 that connectsthe CPU 301, the ROM 302, the RAM 303, the non-volatile memory 304, andthe I/O circuit 305. The inspector terminal 101 may operate on anexternal power source unlike the nodes or may operate on an internalpower source. The non-volatile memory 304 stores therein a nodeidentification information list of the nodes in the system 100.

The I/O circuit 305 is connected to the wireless communications circuit311 and the antenna 312, and to the network I/F 313. Thus, the inspectorterminal 101 can wirelessly communication with the nodes, via thewireless communications circuit 311 and the antenna 312. The wirelesscommunications circuit 311 may be a communications circuit that employsshort range radio enabling communication with nodes within a vicinity ofseveral tens of centimeters, or a communications circuit that employsintermediate range radio enabling communication with nodes at a fartherdistance. The inspector terminal 101, via the network I/F 313, and usingan Internet Protocol (IP) process through a network 314 such as theInternet, can communicate with an external apparatus such as a server.

FIG. 4 is a block diagram depicting a functional example of the systemaccording to the first embodiment. The system 100 includes a chargingunit 401, a receiving unit 411, an executing unit 412, a determiningunit 413, and a transmitting unit 414. Functions of the receiving unit411 to the transmitting unit 414 forming a control unit are realized byexecuting on the MCU 201, programs stored in a storage apparatus. Thestorage apparatus, more specifically, for example, is the ROM 205, theRAM 204, the non-volatile memory 206 depicted in FIG. 2, etc. Thecharging unit 401 is included in slave #a_N and slave #b_N. The chargingunit 401 corresponds to the battery 209 described with reference to FIG.2. The receiving unit 411 to the transmitting unit 414 are included inmaster #1.

The receiving unit 411 receives from slave #a_N, which communicatesdirectly with master #1, a result of the first process executed by slave#a_N. Further, the receiving unit 411 receives from slave #b_N, whichcommunicates directly with master #1, a result of a second processexecuted by slave #b_N. The second process, similar to the firstprocess, is processing assigned by master #0. The received results arestored to a storage area such as the RAM 204 and the non-volatile memory206 of master #1, etc.

The executing unit 412 executes a given process based on the result ofthe first process received by the receiving unit 411. Further, theexecuting unit 412 may execute the given process based on the result ofthe first process and the result of the second process, if the result ofthe second process is received from slave #b_N before determining thatthe given period has elapsed. The result of the given process is storedto a storage area such as the RAM 204 and the non-volatile memory 206 ofmaster #1, etc.

The determining unit 413 determines whether the given period has elapsedsince the receiving unit 411 received the result of the first process.Further, the determining unit 413 may determine whether the given periodhas elapsed since the receiving unit 411 received the result of thesecond process. The determination result is stored to a storage areasuch as the RAM 204 and the non-volatile memory 206 of master #1, etc.

The transmitting unit 414 transmits the result of the given process toslave #a_N, if the determining unit 413 has determined that the givenperiod has elapsed since the result of the first process was received.Further, the transmitting unit 414 may transmit the result of the givenprocess to slave #a_N, #b_N, if the determining unit 413 has determinedthat the given period has elapsed since the result of the second processwas received. The result of the given process may be included in a newprocess execution request to slave #a_N.

FIG. 5 is a diagram depicting a sequence of distributed processing ofthe nodes according to the first embodiment. In the example depicted inFIG. 5, distributed processing on a communication path configured bymaster #0, slave #a_0, slave #a_1, . . . , slave #a_N−1, slave #a_N, andmaster #1 will be described.

Master #0 executes a job assignment process according to the firstembodiment (step S501). Details of the job assignment process accordingto the first embodiment will be described with reference to FIG. 7.Hereinafter, processing assigned to the nodes will be referred to as ajob. The job assignment process is a process of generating jobs andassigning the jobs to plural slaves. Information included in a job willbe described with reference to FIG. 6. In the job assignment process,master #0 transmits a job to plural slaves that include slave #a_0. Morespecifically, the plural slaves are assumed to include slaves #a_0,#b_0, #c_0, #d_0, and #e_0. After the transmission, master #0 hasconsumed power and therefore, suspends operation until charging has beencompleted.

Having received the job, slave #a_0 executes a job execution process(step S502). Details of the job execution process will be described withreference to FIG. 8. In the job execution process, slave #a_0 transfersthe job to the subsequent node. In this manner, the job is successivelytransferred. After the transfer, slave #a_0 has consumed power andtherefore, suspends operation until charging has been completed.

Here, the subsequent node will be described. As described with referenceto FIG. 1, in the system 100, communication paths for data between theslaves are predetermined, and the slaves have stored in a storageapparatus, i.e., the non-volatile memory 206, the identificationinformation of the two nodes with which data is communicated. The slavesreceive a job from one of the two nodes identified from theidentification information stored in the non-volatile memory 206 andtransfer the job to the other of the two nodes as the subsequent node.

Having received the job, slave #a_N executes the job execution process(step S503). In the job execution process, slave #a_N transfers the jobto master #1. After the transfer, slave #a_N has consumed power andtherefore, suspends operation until charging has been completed.

Having received the job, master #1 executes a job aggregation andreassignment process (step S504). Master #1 receives the job from pluralslaves including slave #a_N. More specifically, the plural slavesinclude slaves #a_N, #b_N, #c_N, #d_N, and #e_N. Details of the jobaggregation and reassignment process will be described with reference toFIG. 9. The job aggregation and reassignment process is a process ofgenerating a new job and assigning the new job to plural slaves afterstanding by until charging of slave #a_N has been completed.

When the charging of slave #a_N has been completed, the charging ofmaster #0, slave #a_0, . . . , slave #a_N−1 has a high likelihood ofalso being completed. In the job aggregation and reassignment process,master #1 transmits the new job to the slaves that include slave #a_N.After the transmission, master #1 has consumed power and therefore,suspends operation until charging has been completed.

Having received the new job, slave #a_N executes the job executionprocess (step S505). In the job execution process, slave #a_N transfersthe new job to the subsequent slave. In this manner, the new job issuccessively transferred. Upon receiving the new job, slave #a_0executes the job execution process (step S506). In the job executionprocess, slave #a_0 transfers the new job to master #0. After thetransfer, slave #a_0 has consumed power and therefore, suspendsoperation until charging has been completed.

Having received the new job, master #0 executes a job aggregationprocess (step S507). Master #0 receives the new job from plural slavesincluding slave #a_0. Details of the job aggregation process will bedescribed with reference to FIG. 10. The job aggregation process is aprocess of standing by until the new job has been received from theslaves and collecting the received new job from the slaves.

With reference to FIG. 6, a job structure defining information includedin a job will be described. The system 100 according to the firstembodiment and a second embodiment is assumed to be able to execute ajob of calculating the variance of sensor data in the system 100.Further, to execute the job of calculating the variance, the system 100according to the first and the second embodiment is assumed to be ableto execute a job of calculating a sum of the sensor data in the system100.

FIG. 6 is a diagram depicting one example of the job structure accordingto the first embodiment. A job structure 601 is program code defininginformation included in the job, according to the first embodiment. Thejob structure 601 includes 4 int-type members. The first member is akind member storing an identifier representing the type of job. In thepresent embodiment, identifiers of the job type include a “summationcalculation” representing the job of calculating the sum of data in thesystem 100 and a “variance calculation” representing the job ofcalculating the sample variance of the data in the system 100.

The second member is a data member that stores data that is theprocessing result of the job. The third member is an average member thatstores an average. The fourth member is a hop member that stores a hopcount, which is a transfer count of the job.

Hereinafter, to simplify description, data stored in the kind member ofa job will be referred to as “job type” and the data stored in the datamember of a job will be referred to as “job data”. Further, data storedin the average member of a job will be referred to as “job average” anddata stored in the hop member of a job will be referred to as “job hopcount”.

Flowcharts of the job assignment process, the job execution process, thejob aggregation and reassignment process, and the job aggregationprocess depicted in FIG. 5 will be described with reference to FIGS. 7to 10.

FIG. 7 is a flowchart depicting an example of a procedure of the jobassignment process according to the first embodiment. The job assignmentprocess according to the first embodiment is a process of assigning ajob to plural slaves. Execution of the job assignment process istriggered by a job execution instruction from the inspector terminal101. Alternatively, the job assignment process may be executedperiodically.

Master #0 generates, according to the job structure 601, a summationcalculation job for which the job type is “summation calculation” (stepS701). Master #0 transmits the generated job to plural slaves (stepS702). After completion of the operation at step S702, master #0 endsthe job assignment process according to the first embodiment. Byexecuting the job assignment process according to the first embodiment,master #0 assigns a job to plural slaves and enables the job to bedistributed and processed in the system 100.

FIG. 8 is a flowchart depicting an example of a procedure of the jobexecution process according to the first embodiment. The job executionprocess according to the first embodiment is a process of executing anassigned job. The job execution process is executed by each of theslaves. With respect to FIG. 8, description will be given for a casewhere any one of the slaves among the plural slaves executes the jobexecution process.

When any one of the following 3 conditions is satisfied, the slave istriggered to execute the job execution process. The first condition isrepresented by flowchart connector A in FIG. 8, and is a case where theslave is the subsequent node of master #0 and the operation at step S702in FIG. 7 has been executed. The second condition is represented byflowchart connector B in FIG. 8, and is a case where the slave is thesubsequent node of another slave, the job execution process has beenexecuted by the other slave, and the operation at step S810 in FIG. 8has been executed. The third condition is represented by flowchartconnector C in FIG. 8, and is a case where the slave is the subsequentnode to master #1 and the operation at step S906 in FIG. 9 has beenexecuted.

The slave receives a job (step S801). Subsequently, the slave confirmsthe job type (step S802). If the job type is the summation calculationjob (step S802: summation calculation job), the slave obtains data fromthe sensor 202 (step S803), and stores the obtained data to thenon-volatile memory 304 (step S804). The slave stores data that is thesum of the obtained data and job data, into the job data (step S805).

If the job type is the variance calculation job (step S802: variancecalculation job), the slave obtains data of the sensor 202 from thenon-volatile memory 304 (step S806). Subsequently, the slave calculatesthe square of the difference of the obtained data and a job average(step S807). The slave stores data that is the sum of the obtained dataand job data, into the job data (step S808).

After completing the operation at step S805 or the operation at stepS808, the slave increments the job hop count (step S809), and transfersthe job to the subsequent node (step S810). After completing theoperation at step S810, the slave ends the job execution processaccording to the first embodiment. By executing the job executionprocess according to the first embodiment, a slave can execute anassigned job.

FIG. 9 is a flowchart depicting an example of a procedure of the jobaggregation and reassignment process according to the first embodiment.The job aggregation and reassignment process according to the firstembodiment is a process of aggregating a job, generating a new job, andassigning the new job to the slaves. The job aggregation andreassignment process is executed by master #1. When the operation atstep S810 is executed by a slave whose subsequent node is master #1,execution of the job aggregation and reassignment process is triggered.

Master #1 receives the job (step S901). Master #1 receives the job fromslaves positioned at the terminus of each communication path.Subsequently, master #1 determines whether a given period has elapsedsince the last reception of the job (step S902). If the given period hasnot elapsed since the last reception of the job (step S902: NO), master#1 transitions to the operation at step S901.

Details of the operations at step S901 and step S902 will be described.In a case of 5 communication paths as depicted in FIG. 1, the job isreceived from 5 slaves. After receiving the job from a first slave,master #1 stands by until the given period elapses from the reception ofthe job from the first slave. While standing by, if master #1 receivesthe job from a second slave, master #1 stands by until the given periodelapses from the reception of the job from the second slave. In thismanner, master #1 receives the job from the 5 slaves.

If the job has been received from a certain extent of the slaves and thegiven period elapses, master #1 assumes step S902: YES and executesprocessing without waiting for the job to be transmitted from all theslaves. The first reason for not waiting for the job to be transmittedfrom all the slaves is that the nodes are low cost and installed in alarge number, and consequently, nodes may have failed and the job maynot be transmitted from a portion of the slaves. Further, by analyzingthe job results received from a certain extent of the slaves, the userof the inspector terminal 101 can sufficiently grasp what is occurringin the given area R.

If the given period has elapsed since the last reception of the job(step S902: YES), master #1 calculates an average of the data from thereceived job data and hop counts (step S903). Master #1 generatesaccording to the job structure 601, a variance calculation job for whichthe job type is “variance calculation” (step S904). Master #1 sets thecalculated average into “job average” for the generated job (step S905).Master #1 transmits the variance calculation job to plural slaves (stepS906). Here, consequent to the operation at step S902, the given periodelapses from the transmission of the job by the slave that was last totransmit the job and therefore, the slaves to which the variancecalculation job is to be transmitted are sufficiently charged and thelikelihood that the slaves can operate is high.

After completing the operation at step S906, master #1 ends the jobaggregation and reassignment process according to the first embodiment.Further, in the operation at step S902, although master #1 stands byuntil the given period elapses after the job is received, master #1 mayexecute the operations at step S903 and at step S904 while standing by.For example, when 2 jobs have been received, as an intermediateoperation of the operation at step S903, master #1 may add the first andthe second job hop counts and add the first and the second job data.

By executing the job aggregation and reassignment process according tothe first embodiment, master #1 aggregates jobs, creates a new job, andcan assign the new job to the slaves after the slaves have beensufficiently charged.

FIG. 10 is a flowchart depicting an example of a procedure of the jobaggregation process. The job aggregation process is a process ofaggregating job results. Master #0 receives a job (step S1001).Subsequently, master #0 determines whether a maximum reception standbyperiod has elapsed since the first reception of the job (step S1002).The maximum reception standby period is a period set to given someallowance in standing by such that the job can be received from pluralslaves. For example, the maximum reception standby period is a fewseconds. In the operation at step S1002, master #0 may determine whetherthe maximum reception standby period has elapsed since the lastreception of the job.

If the maximum reception standby period has not elapsed since the firstreception of the job (step S1002: NO), master #0 transitions to theoperation at step S1001. If the maximum reception standby period haselapsed since the first reception of the job (step S1002: YES), master#0 calculates sample variance of the data from the received job data andhop counts (step S1003). After completing the operation at step S1003,master #0 ends the job aggregation process.

The job aggregation process does not include an operation oftransmitting the job to other nodes. Consequently, consideration neednot be given to other nodes being inoperable consequent to insufficientcharging and therefore, determination of whether the given period haselapsed need not be performed. Execution of the job aggregation processenables the system 100 to obtain aggregated results of a job that isdistributed and executed.

As described, according to the system 100, after a processing result isreceived from a slave and a given period has elapsed, another processingresult is transmitted to the slave whereby, the system 100 canefficiently execute distributed processing using nodes that operateintermittently. For example, master #1 can pass a processing result toslave #a_N, without issuing a signal inquiring whether slave #a_N isoperating.

Further, the system 100 gives the task of a master to each node at theterminus of a specified communication path, enabling distributedparallel processing via nodes present as slaves between the masters.

According to the system 100, after receiving the result of a givenprocess from a given slave, if the result of another process fromanother slave is received before the given period has elapsed, master #1may perform a process based on the result of the given process and theresult of the other process. Consequently, master #1 can calculate aresult of aggregated processing results from plural slaves.

The system 100 according to the first embodiment assumes that there arespecified nodes to be masters. On the other hand, the system 100according to the second embodiment assumes that there is 1 specifiednode to be a master. Hereinafter, a system 1100 according to the secondembodiment will be described with reference to FIGS. 11 to 17. Portionsidentical to those described in the first embodiment are given the samereference numerals used in the first embodiment, and description anddepiction thereof is omitted hereinafter.

FIG. 11 is a diagram depicting an operation example of the distributedprocessing method according to the second embodiment. As represented byreference character (a) in FIG. 11, the given area R in which the nodesincluded in the system 1100 according to the second embodiment aredisposed forms the surface of a cylinder. As represented by referencecharacter (a) in FIG. 11, there is 1 master, master #0. Further, theslaves include slaves #a_0 to #a_N, #b_0 to #b_N, #c_0 to #c_N, #d_0 to#d_N, and #e_0 to #e_N. Reference character (b) in FIG. 11 depicts thesurface of the cylinder of reference character (a) in FIG. 11, expandedsuch that master #0 is the start and end of the communication paths. Thespecified communication paths represented by reference character (b) inFIG. 11 are assumed to be 5 in the description hereinafter.

The first communication path is a ring communication path configured bymaster #0, slave #a_0 to #a_N, and master #0. The second communicationpath is a ring communication path configured by master #0, slave #b_0 to#b_N, and master #0. The third communication path is a ringcommunication path configured by master #0, slave #c_0 to #c_N, andmaster #0. The fourth communication path is a ring communication pathconfigured by master #0, slave #d_0 to #d_N, and master #0. The fifthcommunication path is a ring communication path configured by master #0,slave #e_0 to #e_N, and master #0.

In this manner, the communication paths represented by referencecharacter (b) in FIG. 11 are ring communication paths having master #0as an origin. Therefore, any one of the slaves excluding the master ofthe communication path determines whether the given period has elapsed.

FIG. 12 is a block diagram depicting a functional example of the systemaccording to the second embodiment. The system 1100 includes thecharging unit 401, a receiving unit 1201, an executing unit 1202, adetermining unit 1203, and a transmitting unit 1204. Functions of thereceiving unit 1201 to the transmitting unit 1204 forming a control unitare realized by executing on the MCU 201, programs stored in a storageapparatus. The storage apparatus, more specifically, for example, is theROM 205, the RAM 204, the non-volatile memory 206 depicted in FIG. 2,etc. The charging unit 401 is included in master #0, slave #a_i−1, slave#a_i, slave #a_i+1. Here, i is an integer that is 0 or more and lessthan a_N. The charging unit 401 corresponds to the battery 209 describedwith reference to FIG. 2. The receiving unit 1201 to the transmittingunit 1204 are included in slave #a_i.

The receiving unit 1201 receives from a first node capable of directcommunication, a result of a first process executed by the node. When iis 1 or greater, the first node is slave #a_i−1. On the other hand, wheni is 0, the first node is master #0. In this case, the first process isa generated process. The received result is stored to a storage areasuch as the RAM 204 and the non-volatile memory 206 of slave #a_i.

The executing unit 1202 executes the second process based on the resultof the first process, if the receiving unit 1201 receives the result ofthe first process. The result of the executed process is stored to astorage area such as the RAM 204 and the non-volatile memory 206 ofslave #a_i.

The determining unit 1203 determines whether the given period haselapsed since the reception of the result of the first process by thereceiving unit 1201. The determination result is stored to a storagearea such as the RAM 204 and the non-volatile memory 206 of slave #a_i.

The transmitting unit 1204 transmits the result of the second process toa second node capable of communicating directly with slave #a_i on thering communication path, if the determining unit 1203 determines thatthe given period has elapsed. If i is less than N, the second node isslave #a_i+1. If i is N, the second node is master #0.

FIG. 13 is a diagram depicting a sequence of distributed processing bythe nodes according to the second embodiment. In the example depicted inFIG. 13, distributed processing on a ring communication path configuredby master #0, slave #a_0, slave #a_1, . . . , slave #a_N−1, slave #a_N,and master #0 will be described.

Master #0 executes the job assignment process according to the secondembodiment (step S1301). Details of the job assignment process accordingto the second embodiment will be described with reference to FIG. 15. Inthe job assignment process, master #0 transmits a job to plural slavesthat include slave #a_0. After the transmission, master #0 has consumedpower and therefore, suspends operation.

Having received the job, slave #a_0 executes the job execution processaccording to the second embodiment (step S1302). Details of the jobexecution process according to the second embodiment will be describedwith reference to FIG. 16. The job execution process according to thesecond embodiment is put on hold until charging of master #0 has beencompleted, if the job is the first to be executed. Further, the nodethat stands by until charging of the master #0 has been completed may beany one of the nodes among slaves #a_0 to #a_N.

During the job execution process, slave #a_0 transfers the job to thesubsequent slave. After the transfer, slave #0 has consumed power andtherefore, suspends operation. In this manner, the job is successivelytransferred. Upon receiving the job, slave #a_N executes the jobexecution process (step S1303). In the job execution process, slave #a_Ntransfers the job to master #0. After the transfer, slave #a_N hasconsumed power and therefore, suspends operation.

Having received the job, master #0 executes the job aggregation andreassignment process according to the second embodiment (step S1304).Master #0 receives the job from the plural slaves including slave #a_N.Details of the job aggregation and reassignment process according to thesecond embodiment will be described with reference to FIG. 17. The jobaggregation and reassignment process according to the second embodimentis put on hold until the job is received from plural slaves, andcollects the jobs received from the slaves. When job reassignment isperformed, the job aggregation and reassignment process according to thesecond embodiment generates a new job and assigns the new job to pluralslaves.

In the job aggregation and reassignment process, master #0 transmits thenew job to plural slaves including slave #a_0. When the new job istransmitted, charging of master #0 has been completed and therefore,there is a high likelihood that the charging of slave #a_0 has also beencompleted. After the transmission, master #0 has consumed power andtherefore, suspends operation.

Having received the new job, slave #a_0 executes the job executionprocess according to the second embodiment (step S1305). The jobexecution process according to the second embodiment is put on holduntil the charging of master #0 has been completed, if the new job isbeing executed for the first time. In the job execution process, slave#a_0 transfers the new job to the subsequent slave. After the transfer,slave #a_0 has consumed power and therefore, suspends operation. In thismanner, the new job is successively transferred. Upon receiving the newjob, slave #a_N executes the job execution process (step S1306). In thejob execution process, slave #a_N transfers the new job to master #0.After the transfer, slave #a_N has consumed power and therefore,suspends operation.

Having received the new job, master #0 executes the job aggregation andreassignment process according to the second embodiment (step S1307).Master #0 receives the new job from the plural slaves including slave#a_N. Master #0, in the job aggregation and reassignment processaccording to the second embodiment, stands by until the job has beenreceived from plural slaves, and collects the jobs received from theplural slaves. A job structure according to the second embodiment anddescribing information included in a job will be described withreference to FIG. 14.

FIG. 14 is a diagram depicting an example of the job structure accordingto the second embodiment. A job structure 1401 is program code defininginformation included in a job according to the second embodiment. Inaddition to the 4 members included in the job structure 601, the jobstructure 1401 includes a job first time member storing a first timeflag indicating whether the job is being executed for the first time inthe system. Hereinafter, to simplify description, data stored in the jobfirst time member will be referred to as “first time flag” of a job.When the first time flag according to the second embodiment is “1”, thejob is being executed for the first time and when the first time flagaccording to the second embodiment is “0”, the job has been executed byanother node.

Flowcharts of the job assignment process, the job execution process, andthe job aggregation and reassignment process depicted in FIG. 13 will bedescribed with reference to FIGS. 15 to 17.

FIG. 15 is a flowchart depicting an example of a procedure of the jobassignment process according to the second embodiment. The jobassignment process according to the second embodiment is a process ofassigning a job to plural slaves. Master #0 generates according to thejob structure 1401, a summation calculation job for which the job typeis “summation calculation” (step S1501). Master #0 sets the job firsttime flag to “1” for the generated summation calculation job (stepS1502). Subsequently, master #0 transmits the generated job to pluralslaves (step S1503). After completing the operation at step S1503,master #0 ends the job assignment process according to the secondembodiment. By executing the job assignment process according to thesecond embodiment, master #0 can assign a job to plural slaves.

FIG. 16 is a flowchart depicting an example of a procedure of the jobexecution process according to the second embodiment. The job executionprocess according to the second embodiment is a process of executing anassigned job. The job execution process according to the secondembodiment is executed by the slaves. With reference to FIG. 16,description will be given for a case where any one of the slaves amongthe plural slaves executes the job execution process.

When any one of the following 3 conditions is satisfied, the slave istriggered to execute the job execution process. The first condition isrepresented by flowchart connector D in FIG. 16, and is a case where theslave is the subsequent node of master #0 and the operation at stepS1503 in FIG. 15 has been executed. The second condition is representedby flowchart connector E in FIG. 16, and is a case where the slave isthe subsequent node of another slave, the job execution process has beenexecuted by the other slave, and the operation at step S1613 in FIG. 16has been executed. The third condition is represented by flowchartconnector F in FIG. 16, and is a case where the slave is the subsequentnode of master #0 and the operation at step S1708 in FIG. 17 has beenexecuted.

The operations at step S1601 and steps S1605 to S1613 of the jobexecution process according to the second embodiment are identical tothe operations at steps S801 to S810 in FIG. 8 and therefore,description thereof is omitted herein.

After completing the operation at step S1601, the slave determineswhether the first time flag for the job is “1” (step S1602). If thefirst time flag is “1” (step S1602: YES), the slave sets the first timeflag to “0” (step S1603). The slave stands by until the given periodelapses (step S1604). The slave may execute operations up to andincluding that at step S1612 while standing by.

After completing the operation at step S1604 or if the first time flagis “0” (step S1602: NO), the slave transitions to the operation at stepS1605. By executing the job execution process according to the secondembodiment, the slaves can execute an assigned job and since the slavesstandby until master #0 is sufficiently charged, the job can betransmitted when master #0 is operating.

FIG. 17 is a flowchart depicting an example of a procedure of the jobaggregation and reassignment process according to the second embodiment.The job aggregation and reassignment process according to the secondembodiment is put on hold until the job is received from plural slaves,collects the job received from the plural slaves, and when jobreassignment is to be performed, generates a new job and assigns the newjob to the plural slaves. The trigger for the execution of the jobaggregation and reassignment process according to the second embodimentis a case where the operation at step S1613 has been executed by a slavewhose subsequent node is master #0.

Further, the operations at steps S1704 to S1706, and step S1708 of thejob aggregation and reassignment process according to the secondembodiment are identical to the operations at steps S903 to S906depicted in FIG. 9 and therefore, description thereof is omitted herein.

Master #0 receives a job (step S1701). Subsequently, master #0determines whether the maximum reception standby period has elapsedsince the first reception of the job (step S1702). If the maximumreception standby period has not elapsed since the first reception ofthe job (step S1702: NO), master #0 transitions to the operation at stepS1701.

If the maximum reception standby period has elapsed since the firstreception of the job (step S1702: YES), master #0 confirms the job type(step S1703). If the job type is a summation calculation job (stepS1703: summation calculation job), master #0 transitions to theoperation at step S1704.

After completing the operation at step S1706, master #0 sets the jobfirst time flag to “1” (step S1707) and transitions to the operation atstep S1708.

If the job type is a variance calculation job (step S1703: variancecalculation job), master #0 calculates sample variance from the receivedjob data and hop counts (step S1709). The value of the sample varianceis stored to the non-volatile memory 304. After completing the operationat step S1709, master #0 ends the job aggregation and reassignmentprocess according to the second embodiment. By executing the jobaggregation and reassignment process according to the second embodiment,the system 1100 can aggregate results of a job that is distributed andexecuted.

As described, according to the system 1100, when plural nodes configurea ring communication path, by having slaves subsequent to master #0standby for a given period, process results can be transmitted whilemaster #0 is operating.

The distributed processing method described in the present embodimentmay be implemented by executing a prepared program on a computer such asa personal computer and a workstation. The program is stored on anon-transitory, computer-readable recording medium such as a hard disk,a flexible disk, a CD-ROM, an MO, and a DVD, read out from thecomputer-readable medium, and executed by the computer. The distributedprocessing program may be distributed through a network such as theInternet.

According to one aspect of the present disclosure, an effect is achievedin that distributed processing can be efficiently performed using pluralcommunications apparatuses that operate using power generated fromenergy obtained corresponding to the environment.

All examples and conditional language provided herein are intended forpedagogical purposes of aiding the reader in understanding the inventionand the concepts contributed by the inventor to further the art, and arenot to be construed as limitations to such specifically recited examplesand conditions, nor does the organization of such examples in thespecification relate to a showing of the superiority and inferiority ofthe invention. Although one or more embodiments of the present inventionhave been described in detail, it should be understood that the variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A distributed processing method of a system inwhich a plurality of communications apparatuses transmits and receivesdata by multi-hop communication, the distributed processing methodcomprising: executing, by a given communications apparatus being amongthe plurality of communications apparatuses, a given calculation processthat is a different kind of calculation process from a first calculationprocess, based on a result of the first calculation process executed bya first communications apparatus that is among the plurality ofcommunications apparatuses, communicates directly with the givencommunications apparatus, and operates using power stored in a chargingdevice charged by power generated from energy obtained corresponding toan environment where the first communications apparatus is installed,the given communications apparatus executing the given calculationprocess when receiving the result of the first calculation process fromthe first communications apparatus; determining, by the givencommunications apparatus, whether a given period has elapsed sincereceiving the result of the first calculation process; transmitting, bythe given communications apparatus, a result of the given calculationprocess to the first communications apparatus when determining that thegiven period has elapsed; and assigning, by the given communicationsapparatus, a second calculation process that is a different kind ofcalculation process from the first and the given calculation processesto the first communications apparatus when determining that the givenperiod has elapsed.
 2. The distributed processing method according toclaim 1, wherein when the given communications apparatus receives theresult of a third calculation process that is a same kind of calculationprocess as the first calculation process, from a second communicationsapparatus before the given communications apparatus determines that thegiven period has elapsed, the second communications apparatus havingexecuted the third calculation process, being among the plurality ofcommunications apparatuses excluding the first communications apparatus,communicating directly with the given communications apparatus, andoperating using power stored in a charging device charged by powergenerated from energy obtained corresponding to an environment where thesecond communications apparatus is installed, the distributed processingmethod comprising: executing, by the given communications apparatus, thegiven calculation process based on the result of the first calculationprocess and the result of the third calculation process, determining, bythe given communications apparatus, whether the given period has elapsedsince receiving the result of the third calculation process from thesecond communications apparatus, and transmitting, by the givencommunications apparatus, the result of the given calculation process tothe first communications apparatus and the second communicationsapparatus, when determining that the given period has elapsed.
 3. Adistributed processing method of a system in which a plurality ofcommunications apparatuses transmits and receives data by multi-hopcommunication, the distributed processing method comprising: executing,by a communications apparatus, a second calculation process based on aresult of a first calculation process, when receiving the result of thefirst calculation process from a first communications apparatus thatexecuted the first calculation process and communicates directly withthe communications apparatus on a ring communication path formed by theplurality of communications apparatuses respectively operating usingpower of a charging device charged by power generated from energyobtained corresponding to an environment where installed, thecommunications apparatus being among the plurality of communicationsapparatuses and specified as an origin on the ring communication path,the second calculation process being different kind of calculationprocess from the first calculation process; determining, by thecommunications apparatus, whether a given period has elapsed sincereceiving the result of the first calculation process; transmitting, bythe communications apparatus, a result of the second calculation processto a second communications apparatus that on the ring communicationspath, communicates directly with the communications apparatus, thecommunications apparatus transmitting the result of the secondcalculation process when determining that the given period has elapsed;and assigning, by the communications apparatus, a third calculationprocess that is different kind of calculation process from the first andthe second calculation process to the second communications apparatuswhen determining that the given period has elapsed.
 4. A system in whicha plurality of communications apparatuses transmits and receives data bymulti-hop communication, the system comprising a given communicationsapparatus that is among the plurality of communications apparatuses andconfigured to include: an executing circuit configured to execute agiven calculation process that is a different kind of calculationprocess from a first calculation process, based on a result of the firstcalculation process executed by a communications apparatus that is amongthe plurality of communications apparatuses, communicates directly withthe given communications apparatus, and operates using power stored in acharging device charged by power generated from energy obtainedcorresponding to an environment where the communications apparatus isinstalled, the executing circuit executing the given calculation processwhen the given communications apparatus receives the result of the firstcalculation process from the communications apparatus; a determiningcircuit configured to determine whether a given period has elapsed sincereception of the result of the first calculation process; a transmittingcircuit configured to transmit a result of the given calculation processexecuted by the executing circuit, to the communications apparatus whenthe determining circuit determines that the given period has elapsed;and an assigning circuit configured to assign a third calculationprocess that is a different kind of calculation process from the firstand the given calculation processes to the first communicationsapparatus when determining that the given period has elapsed.
 5. Asystem in which a plurality of communications apparatuses transmits andreceives data by multi-hop communication, the system comprising acommunications apparatus that is among the plurality of communicationsapparatuses and specified as an origin on a ring path formed by theplurality communications apparatuses respectively operating using powerof a charging device charged by power generated from energy obtainedcorresponding to an environment where installed, the communicationsapparatus configured to include: an executing circuit configured toexecute a second calculation process based on a result of a firstcalculation process, when the communications apparatus receives theresult of the first calculation process from a first communicationsapparatus that executed the first calculation process and thatcommunicates directly with the communications apparatus on the ringcommunication path, the second calculation process being different kindof calculation process from the first calculation process; a determiningcircuit configured to determine whether a given period has elapsed sincereception of the result of the first calculation process; a transmittingcircuit configured to transmit a result of the second calculationprocess executed by the executing circuit, to a second communicationsapparatus that on the ring communication path, communicates directlywith the communications apparatus, the transmitting circuit transmittingthe result of the second calculation process when the determiningcircuit determines that the given period has elapsed; and an assigningcircuit configured to assign a third calculation process that is adifferent kind of calculation process from the first and the secondcalculation processes to the first communications apparatus whendetermining that the given period has elapsed.
 6. A non-transitory,computer-readable recording medium storing therein a distributedprocessing program of a system in which a plurality of communicationsapparatuses transmits and receives data by multi-hop communication, thedistributed processing program causing a given communications apparatusamong the plurality of communications apparatuses to execute a processcomprising: executing a given calculation process that is a differentkind of calculation process from a first calculation process, based on aresult of the first calculation process executed by a communicationsapparatus that is among the plurality of communications apparatuses,communicates directly with the given communications apparatus, andoperates using power stored in a charging device charge by powergenerated from energy obtained corresponding to an environment where thecommunications apparatus is installed, the given calculation processbeing executed when the given communications apparatus receives theresult of the first calculation process from the communicationsapparatus; determining whether a given period has elapsed sincereception of the result of the first calculation process; andtransmitting a result of the given calculation process to thecommunications apparatus, when determining that the given period haselapsed; and assigning a second calculation process that is a differentkind of calculation process from the first and the given calculationprocesses to the first communications apparatus when determining thatthe given period has elapsed.
 7. A non-transitory, computer-readablerecording medium storing therein a distributed processing program of asystem in which a plurality of communications apparatuses transmits andreceives data by multi-hop communication, the distributed processingprogram causing a communications apparatus among the plurality ofcommunications apparatuses to execute a process comprising: executing asecond calculation process based on a result of a first calculationprocess, when the communications apparatus receives the result of thefirst calculation process from a first communications apparatus thatexecuted the first calculation process and communicates directly withthe communications apparatus on a ring communication path formed by theplurality communications apparatuses respectively operating using powerof a charging device charged by power generated from energy obtainedcorresponding to an environment where installed, the communicationsapparatus being among the plurality of communications apparatuses andspecified as an origin on the ring path, the second calculation processbeing different kind of calculation process from the first calculationprocess; determining whether a given period has elapsed since receptionof the result of the first calculation process; and transmitting aresult of the second calculation process to a second communicationsapparatus that on the ring communication path, communicates directlywith the communications apparatus, the result of the second calculationprocess being transmitted when determining that the given period haselapsed; and assigning a third calculation process that is differentkind of calculation process from the first and the second calculationprocess to the second communications apparatus when determining that thegiven period has elapsed.